Error executing task

There's a corrupt item entity in your world, but I don't know whether that's the cause.
And also, what were you trying?

Nop, nop and nothing. I just tried to play single play.

BTW the keyboard controls does not working.

[16:57:28] [Client thread/ERROR]: Item entity 496060 has no item?!

The big number makes me worried, maybe your world is overloaded with a extreme amount of entities.

Searched the code, of course it's impossible to read, but I think you (or Minecraft) are (or was) out of memory